Nano-sized Samples Research Articles

Size-dependent anatase to rutile phase transition under acoustic shocked conditions – A case study of TiO2 bulk and nanoparticles

In the present work, we attempt to explore the size-dependent structural stability of bulk (0.28 µm) and nano-sized (25 nm) anatase TiO2 particles under acoustic shocked conditions. Based on the observed X-ray diffractometric, Raman spectroscopic and transmission electron microscopic results with respect to the number of shock pulses, at the 90-shocked condition, the nano-size particles undergo the anatase to the rutile phase transition, whereas the bulk size TiO2 particles remain to be in the anatase phase. From the comprehensive assessment, it is demonstrated that the bulk TiO2 samples have higher structural stability compared to the nano-size samples. The nano-sized anatase-TiO2particles have values of lower thermal conductivity compared to the bulk-sized particles such that the value of lower thermal conductivity is a prominent crucial factor in initiating the dynamic recrystallization which results in the anatase-to-rutile phase transition. Based on the observed present experimental results and previous reports, it has been authenticated that, while increasing the particle size from nano-scale to micro-scale, the critical shock number for the anatase to rutile phase transition is significantly increased.

Near-room-temperature magnetic properties and magnetocaloric effect of polycrystalline and nano-scale manganites Pr(0.65-x)NdxSr0.35MnO3 (x ≤ 0.35)

Here we report investigations of structural, electrical and magnetic properties of bulk and nano-sized Pr0.65-xNdxSr0.35MnO3 compounds (x ≤ 0.35). Polycrystalline compounds were produced by solid – state reaction and nanocrystalline samples were obtained by sol–gel method. Analysis of x-ray diffraction patterns revealed a change in lattice structure from ‘Pbnm’ to ‘R3c’ symmetry, with diminishing cell volume upon increasing Nd ions substitution for all samples. Optical microscopy was used for bulk surface morphology and transmission electron microscopy was implemented for nano-sized samples. Iodometric titration showed oxygen deficiency for bulk compounds and oxygen excess for nano-sized particles. Measurements of resistivity of bulk samples revealed a single peak at temperatures associated with grain boundary conditions and with ferromagnetic/paramagnetic transition and negative magnetoresistivity. Critical magnetic behavior analysis disclosed that the polycrystalline samples are governed by a tricritical mean field and by 3D Heisenberg models while nanocrystalline samples are governed by a mean field model. Curie temperature Tc values remain in near room temperature range for all bulk compounds; they lower with increasing Nd ions substitution from 295 K for the parent bulk compound to 268 K for x = 0.35. Tc is lowered from 255 K for the parent nano-sized compound in small temperature intervals. All compounds exhibit second-order magnetic phase transitions and relatively high magnetic entropy change, with the highest value of 5.74 J/kgK for x = 0.25 bulk sample in μ˳∆H = 4 T. Strong magnetocaloric effect, stability and the possibility of fine-tuning Tc by Nd ions substitution make the investigated bulk polycrystalline compounds promising for application in magnetic refrigeration. Nano-sized samples possess lower magnetic entropy changes of maximum 2.4 J/kgK in μ˳∆H = 4 T for x = 0.15, but wider effective entropy change temperature (δTfwhm) and relative cooling power on par with other manganites, bringing them into the conversation as a viable option in cooling materials.

Controllable synthesis of carbon supported cobalt monoxide anode and high-voltage lithium cobalt oxide cathode with enhanced lithium-ion storage

Natural macromolecule amylose (AM) is employed to deoxygenate few-layered graphene oxide (GO) and modulate the surface interaction between GO sheets and Co2+ ions under mild hydrothermal conditions. The obtained Co2+ ions and AM molecule jointly decorated reduced graphene oxide (Co-AM/RGO) sample is further utilized to synthesize both anode and cathode materials with controlled microstructures. To synthesize anode material, the Co-AM/RGO can be directly converted to a hierarchical AM pyrolyzed carbon and RGO supported cobalt monoxide nanocomposite (CoO@AMC/RGO) after a simple inert gas protected thermal treatment. To synthesize cathode material, a carbon coated nano-sized lithium cobalt oxide sample (LiCoO2/C, LCO/C) can be obtained after a solid-state reaction in air by mixing lithium salt with the Co-AM/RGO. The CoO and LCO nanocrystals with significantly controlled sizes are well dispersed in the carbon matrices. The CoO@AMC/RGO anode shows a high reversible capacity of 785.25 mAh·g−1 after 500 cycles at 200 mA·g−1 and 608.25 mAh·g−1 after 700 cycles at 1000 mA·g−1, while the LCO/C cathode delivers a superior reversible capacity of 140.91 mAh·g−1 after 1000 cycles at 1000 mA·g−1 with a high cut-off voltage of 4.6 V. This work provides a new perspective for controllable engineering of electrode materials with enhanced lithium-ion storage performances.

Effect of annealing time on the structural stability of LiCo0.55Ni0.4Ti0.05O2 cathode material via combustion method

Layered LiNi1-xCoxO2 cathode material, particularly LiCo0.6Ni0.4O2 (LCN) in stoichiometry is one of the promising cathode materials as it possesses a good electrochemical behaviour and performances comparable with commercial LiCoO2 (LCO) cathode material. However, more improvement needs to be done in LCN cathode material in terms of higher toxic Co content and higher cation mixing in the material which mainly contributes to the structural instability and affects the capacity fading of the material. To combat both significant issues in the material, the stability of that material structure needs to be tackled first. In this study, Co was partially substituted with Ti4+ to give the LiCo0.55Ni0.4Ti0.05O2 (LCNT) cathode material using the combustion method. To get the optimum condition of LCNT, the precursor was then calcined at a temperature of 750°C for 24 hours, 48 hours and 72 hours and denoted as LCNT24, LCNT48, and LCNT72 respectively. XRD reveals that all samples are pure, single-phase with no impurities present except for LCNT72. Nano-sized LCNT24 sample has the highest RIR value of 1.84 indicating the lowest degree of cation Li+/Ni2+ mixing in the material and the most stable structure compared to others.

Synthesis and electrochemical characteristics of almost stoichiometric nanosized cathode materials Li1-xNi1+xO2 with a combination of sol-gel and solid-phase methods

We have found approaches to the synthesis of cheap near-stoichiometric lithium nickelate (LiNiO2). The resulting phases have been identified by X-ray phase analysis. Obtained materials have been studied by spectrometric method; electron microscopy; BET method; impedance spectroscopy. A technological scheme has been developed, the optimal conditions for the combined synthesis of lithium nickelate close to the stoichiometric composition Li0.98Ni1.02О2 have been determined. We have proved that nanosized samples with a well-developed surface form during such a synthesis. We have determined that the electrochemical characteristics of the samples correspond to those of lithium nickelate used in commercial electrochemical cells.

Atomic Force Microscopy: An Introduction.

Imaging of nano-sized particles and sample features is crucial in a variety of research fields, for instance, in biological sciences, where it is paramount to investigate structures at the single particle level. Often, two-dimensional images are not sufficient, and further information such as topography and mechanical properties are required. Furthermore, to increase the biological relevance, it is desired to perform the imaging in close to physiological environments. Atomic force microscopy (AFM) meets these demands in an all-in-one instrument. It provides high-resolution images including surface height information leading to three-dimensional information on sample morphology. AFM can be operated both in air and in buffer solutions. Moreover, it has the capacity to determine protein and membrane material properties via the force spectroscopy mode. Here we discuss the principles of AFM operation and provide examples of how biomolecules can be studied. New developments in AFM are discussed, and by including approaches such as bimodal AFM and high-speed AFM (HS-AFM), we show how AFM can be used to study a variety of static and dynamic single biomolecules and biomolecular assemblies.

Influence of sintering temperature on structural and optical properties of Cd0.5Cu0.5CrxFe2−xO4 ferrites

Two ferrite series were synthesized. One series has nanosize samples that have been prepared by the co-precipitation method, and the second series has the corresponding bulk samples that have been sintered at 1000 °C for 6 h. X-ray diffraction has been used to estimate the cubic spinel structure of both series. The crystallite size, theoretical density, and porosity of the nanomaterials are larger than those of the bulk materials. HRTEM analysis demonstrated the aggregation of nanoscale samples, including an average particle size of 9–22.5 nm. However, bulk specimens have a limited surface area. The agglomeration of the nanoparticles was seen in TEM images, in which the mean particle size was within the limit of the crystallite size (R) result and ranged from 14 to 20 nm. The appearance of the spinel phase in the samples was validated through Raman spectroscopy. Different cation occupation ratios in either tetrahedral or octahedral sites have been identified to be associated with an observable systematic shift and asymmetric flattening in Raman spectra with a variation in Cr3+ concentration. The optical characterization was performed using the UV/Vis methodology, and the results reveal that the absorption cutoff frequency declines as the chromium content rises. It was also estimated that the optical bandgap averaged 3.6 eV for nanosamples and 4.6 eV for overall bulk materials. The highest photoluminescence emission was seen at wavelengths between λem = 415 and 460 nm. The photoluminescence emission peaks of both bulk and nanoscale materials were red-shifted. These results accurately reflect the corresponding energy gap values for almost the same ranges. Sintering leads to a rise in photoluminescence.

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Bulk Manganites La0.7Ba(0.3−x)CaxMnO3 (x ≤ 0.25)

Here we report the synthesis and investigation of bulk and nano-sized La0.7Ba0.3−xCaxMnO3 (x = 0, 0.15, 0.2 and 0.25) compounds that are promising candidates for magnetic refrigeration applications. We compare the structural and magnetic properties of bulk and nano-scale polycrystalline La0.7Ba0.3−xCaxMnO3 for potential use in magnetic cooling systems. Solid-state reactions were implemented for bulk materials, while the sol–gel method was used for nano-sized particles. Structurally and morphologically, the samples were investigated by X-ray diffraction (XRD), optical microscopy and transmission electron microscopy (TEM). Oxygen stoichiometry was investigated by iodometry. Bulk compounds exhibit oxygen deficiency, while nano-sized particles show excess oxygen. Critical magnetic behavior was revealed for all samples using the modified Arrott plot (MAP) method and confirmed by the Kouvel–Fisher (KF) method. The bulk polycrystalline compound behavior was better described by the tricritical field model, while the nanocrystalline samples were governed by the mean-field model. Resistivity in bulk material showed a peak at a temperature Tp1 attributed to grain boundary conditions and at Tp2 associated with a Curie temperature of Tc. Parent polycrystalline sample La0.7Ba0.3MnO3 has Tc at 340 K. Substitution of x = 0.15 of Ca brings Tc to 308 K, and x = 0.2 brings it to 279 K. Nanocrystalline samples exhibit a very wide effective temperature range in the magnetocaloric effect, up to 100 K. Bulk compounds exhibit a high and sharp peak in magnetic entropy change, up to 7 J/kgK at 4 T at Tc for x = 0.25. To compare the magnetocaloric performances of the studied compounds, both relative cooling power (RCP) and temperature-averaged entropy change (TEC) figures of merit were used. RCP is comparable for bulk polycrystalline and nano-sized samples of the same substitution level, while TEC shows a large difference between the two systems. The combination of bulk and nanocrystalline materials can contribute to the effectiveness and improvement of magnetocaloric materials.

Size effect on magnetism and large magnetocaloric effect of Haldane chain antiferromagnet Er2BaNiO5

We investigated the size effect on magnetocaloric effect (MCE) of Haldane spin-chain antiferromagnet Er2BaNiO5. The bulk sample was prepared by solid state route and the nano-size samples (N-4 h, N-8 h) were produced by using the high-energy planetary ball mill machine. The crystal structure was obtained by the refinement of XRD results and the SEM images. The present magnetization results indicated that the decreasing of average crystallite size induced enhancement of magnetization and paramagnetic-like behavior. The zero-approaching of θp values for N-8 h revealed the suppression of the dominant antiferromagnetic (AFM) interactions in bulk sample. The fitting results of Haldane gap stated clearly its dramatical reduction which is consistent with the weaken of magnetic interactions. The size effect also presented great influence on MCE. The negative MCE in bulk sample disappeared and instead of monotonically increasing of MCE in N-4 h and N-8 h samples. The maximum entropy change (-ΔSmax) of N-8 h increased nearly 3.2 times compared to bulk sample. The increasing of PM ions in nano-samples were verified by the ESR results, in which the bulk sample showed unavailable ESR signals due to the complex competing 3D AFM interactions. While for the nano-samples, the ESR signals of Er3+ and Ni2+ ions were observed with the g value of gEr = 6.1 and gNi = 2.28. The size-effect on MCE in Er2BaNiO5 opened new approach of the research on magnetic refrigeration.

Measurement and modeling of water vapor sorption on nano-sized coal particulates and its implication on its transport and deposition in the environment

One major cyclical environmental parameter within the underground mine space is the fluctuation of relative humidity, which varies daily and seasonally. Therefore, moisture and dust particle interactions are inevitable and indirectly control dust transport and fate. After being released into the environment, the coal dust particles stay there for a long period depending upon several parameters such as particle size, specific gravity, ventilation etc. Due to their smaller size, nano-sized coal dust particles could remain in the mine environment indefinitely while interacting with it. Correspondingly the primary characteristic of nano-sized coal dust particles could get modified. The nano-sized coal dust samples were prepared in the lab and characterized using different techniques. The prepared samples were allowed to interact with moisture using the dynamic vapor sorption technique. It was found that the lignite coal dust particles could adsorb up to 10 times more water vapor than the bituminous coal dusts. Oxygen content is one of the primary factors in deciding the total effective moisture adsorption in the nano-sized coal dust, with moisture adsorption proportional to the oxygen content of the coal. This means that lignite coal dust is more hygroscopic when compared to bituminous coal dust. GAB and Freundlich's models perform well for water uptake modeling. Because of interaction with atmospheric moisture, particularly swelling, adsorption, moisture retention, and particle size changes, such interactions will significantly change the physical characteristics of nano-sized coal dust. This will affect the transport and deposition behavior of coal dust in the mine atmosphere.

Magnetic Properties and Magnetocaloric Effect of Polycrystalline and Nano-Manganites Pr0.65Sr(0.35-x)CaxMnO3 (x ≤ 0.3).

Here we report investigations of bulk and nano-sized Pr0.65Sr(0.35-x)CaxMnO3 compounds (x ≤ 0.3). Solid-state reaction was implemented for polycrystalline compounds and a modified sol-gel method was used for nanocrystalline compounds. X-ray diffraction disclosed diminishing cell volume with increasing Ca substitution in Pbnm space group for all samples. Optical microscopy was used for bulk surface morphology and transmission electron microscopy was utilized for nano-sized samples. Iodometric titration showed oxygen deficiency for bulk compounds and oxygen excess for nano-sized particles. Measurements of resistivity of bulk samples revealed features at temperatures associated with grain boundary condition and with ferromagnetic (FM)/paramagnetic (PM) transition. All samples exhibited negative magnetoresistivity. Magnetic critical behavior analysis suggested the polycrystalline samples are governed by a tricritical mean field model while nanocrystalline samples are governed by a mean field model. Curie temperatures values lower with increasing Ca substitution from 295 K for the parent compound to 201 K for x = 0.2. Bulk compounds exhibit high entropy change, with the highest value of 9.21 J/kgK for x = 0.2. Magnetocaloric effect and the possibility of tuning the Curie temperature by Ca substitution of Sr make the investigated bulk polycrystalline compounds promising for application in magnetic refrigeration. Nano-sized samples possess wider effective entropy change temperature (ΔTfwhm) and lower entropy changes of around 4 J/kgK which, however, puts in doubt their straightforward potential for applications as magnetocaloric materials.

Influence of Fe<sub>3</sub>O<sub>4</sub> on Physicochemical and Photocatalytic Properties of Nanosized Barium Titanate

A procedure has been proposed for the synthesis of a nanocomposite based on barium titanate modified by adding nanodispersed magnetite using the sol–gel method in an acetic acid medium followed by annealing at 800°C. The physicochemical analysis of the products has shown that the matrix phase after annealing is barium titanate with an admixture of barium carbonate, and, in addition to magnetite, there are minor inclusions of hematite and wustite. The elemental composition of nanosized samples has been determined using energy-dispersive X-ray spectroscopy. It has been demonstrated that the concentration of introduced Fe3O4 affects the morphological and phase composition of the composites. The specific surface area and type of porosity of calcined samples have been determined by the low-temperature nitrogen adsorption/desorption method. The effect of BaTiO3, BaTiO3/Fe3O4-1%, and BaTiO3/Fe3O4-10% powders on the adsorption capacity and photocatalytic activity in the process of decolorization of the dye rhodamine B from an aqueous solution in the dark and under the action of ultraviolet light has been studied. The kinetics of adsorption in the dark and photocatalytic decomposition of rhodamine B under the action of ultraviolet radiation in an aqueous suspension of the obtained composites have been analyzed using pseudo-first and pseudo-second order kinetic models.

Grain growth kinetics of the gamma phase metallic uranium

Metallic uranium is a leading fuel form for sodium cooled fast reactors as an enabling technology of future nuclear energy systems. Mechanistic understanding of fuel behaviors and kinetics under thermodynamic equilibrium and highly non-equilibrium conditions are essential for evaluating fuel performance. It is important to understand and predict the grain and pore evolutions of metallic fuels under thermal and irradiation conditions. However, very limited data are available on the grain growth kinetics and mechanisms of pure gamma phase uranium. In this paper, the pure gamma uranium pellets with different grain structures were fabricated by combining high-energy ball milling and spark plasma sintering. Isothermal annealing tests were performed to investigate the grain growth behavior of the pure gamma phase uranium with different initial grain sizes. A parabolic relationship in grain growth with time was identified for the submicron-sized (374 nm) sample. In contrast, for the nano-sized (137 nm) sample, the grain growth shows a linear relationship with time. The activation energies of grain growth were determined as 199.5 KJ/mol and 80.6 KJ/mol for nano-sized and submicron-sized grain structures, respectively. For the nano-sized sample, the rate-control step of grain growth is dominated by the triple-junction migration, in which the grain boundary triple junction drags the grain growth, leading to a higher activation energy than the bulk diffusion. The dominating mechanism for the submicron-sized sample is grain boundary diffusion. The mechanistic understanding and critical data obtained on the kinetics of pure uranium phases will be useful to evaluate fuel behavior under thermodynamic equilibrium conditions and develop a high fidelity model to predict fuel performance.

Investigation The Effect of Particle Size and Annealing on the Performance of Nano/Micro Sized ZnO-Based Varistors

In this study, the influence of different ZnO particle sizes and the oxygen annealing process on the microstructure, and electrical properties of ZnO-based varistors was investigated. ZnO-Bi2O3-Mn2O3 discs based varistors with different size of ZnO particles were prepared by conventional ceramic method. Then half of varistors discs were annealed in oxygen atmosphere at 700 °C. SEM, Raman spectroscopy, and current-voltage (I–V) measurement were used. The results showed a significant improvement in distribution and growth of grain sizes in nano-size samples compared to that of micro-size samples. The electrical properties including nonlinear coefficient and breakdown voltage improved to 49 and 2555 V in nano-size compared with 32.5 and 201V in micro-size.

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Manganites La(0.7-x)EuxBa0.3MnO3.

Here, we report synthesis and investigations of bulk and nano-sized La(0.7-x)EuxBa0.3MnO3 (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La(0.7-x)EuxBa0.3MnO3, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La0.7Ba0.3MnO3, has Curie temperature TC = 340 K. The magnetocaloric effect is at its maximum around TC. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40-80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition TC = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower TC values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained.

Electron-Phonon Coupling and Nonthermal Effects in Gold Nano-Objects at High Electronic Temperatures.

Laser irradiation of metals is widely used in research and applications. In this work, we study how the material geometry affects electron–phonon coupling in nano-sized gold samples: an ultrathin layer, nano-rod, and two types of gold nanoparticles (cubic and octahedral). We use the combined tight-binding molecular dynamics Boltzmann collision integral method implemented within XTANT-3 code to evaluate the coupling parameter in irradiation targets at high electronic temperatures (up to Te~20,000 K). Our results show that the electron–phonon coupling in all objects with the same fcc atomic structure (bulk, layer, rod, cubic and octahedral nanoparticles) is nearly identical at electronic temperatures above Te~7000 K, independently of geometry and dimensionality. At low electronic temperatures, reducing dimensionality reduces the coupling parameter. Additionally, nano-objects under ultrafast energy deposition experience nonthermal damage due to expansion caused by electronic pressure, in contrast to bulk metal. Nano-object ultrafast expansion leads to the ablation/emission of atoms and disorders the inside of the remaining parts. These nonthermal atomic expansion and melting are significantly faster than electron–phonon coupling, forming a dominant effect in nano-sized gold.

Improved pechini sol-gel fabrication of Li2B4O7/NiO/Ni3(BO3)2 nanocomposites to advanced photocatalytic performance

In current research, nano-scaled Li 2 B 4 O 7 /NiO/Ni 3 (BO 3 ) 2 (LiBNi) composites were fabricated through improved pechini sol–gel method for advanced photocatalytic applications to remove dye contaminations of drinking water under UV/Visible irradiation. To optimize LiBNi nanocomposites properties, different complexing agents including ethylenediaminetetraacetic acid (EDTA), citric acid, tannic acid, tartaric acid and phthalic acid were utilized in pechini sol–gel process. Various sizes and morphologies of Li 2 B 4 O 7 /NiO/Ni 3 (BO 3 ) 2 nanocomposites obtained that were characterized by SEM and TEM techniques. Also, to confirm crystalline and structural features of nano-sized LiBNi samples, analyses of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and energy dispersive X-ray (EDX) were performed. By consideration of UV–Vis data, band-gap of LiBNi nanocomposites premeditated is 3.35 eV. Moreover, photocatalytic degradation of Li 2 B 4 O 7 /NiO/Ni 3 (BO 3 ) 2 nanocomposites was examined via UV/visible waves in aqueous solution for degradation acid red 88 pollutant after 90 min. Some operative factors such as nanocatalyst concentration and irradiation type for optimized LiBNi nanocomposites were assessed for removal of drinking water contaminant.

Experimental investigation of phase equilibria of the Ir-Pt binary system in subsolidus region

Binary phase diagram Ir-Pt system has a wide miscibility gap whose boundaries are difficult to determine due to low diffusion of refractory metals. The system itself has a number of potential applications primarily in catalysis, where addition of iridium to pure platinum promotes higher activity. Therefore, the information about thermodynamic stability of bimetallic particles is necessary for research in this area.The Ir-Pt system was reinvestigated in subsolidus region by means of X-ray diffraction, SEM and TEM. The true equilibrium state of solid solutions in miscibility gap region was achieved via double-sided approach. Pairs of samples, mixture of pure metals and single-phase solid solution, were annealed at different temperatures until the equal phase composition is reached. To shorten annealing time needed for reaching the state of equilibrium, the porous nanosized samples were used, which were prepared from the mixture {(NH4)2[PtCl6] + (NH4)2[IrCl6]} and solid solution of corresponding complex salts(NH4)2[Ir0.5Pt0.5Cl6]. The temperature range was 600–1400 °C. The boundaries of miscibility gap revealed to be significantly lower than stated before, the critical point position was estimated to be ~ 790 °C at 55 at% Pt. The approach can be suitable for investigation in other refractory metals binary systems.

Preparation and radiation attenuation properties of ceramic ball clay enhanced with micro and nano ZnO particles

The radiation shielding properties of ball clays produced with various percentages of 5, 10, 15, and 20 w.t% of micro and nano ZnO were experimentally evaluated in this paper. The effects of micro and nano ZnO on the attenuation competence of the prepared ball clays were compared. At all energies, we discovered that the ball clay with nano ZnO has a higher linear attenuation coefficient (LAC) than ZnO with microparticles. This finding suggests that nano-sized ZnO-ball clay samples absorbed more photons than microsized ZnO ball clay samples. The half-value layer (HVL) for the ball clay prepared with micro and nano ZnO was reported. At all the energies tested, we discovered that the ball clay with nano ZnO has a slightly lower HVL than the ball clay with micro ZnO. The HVL at 0.06 MeV is found to be 0.934 cm for the ball clay containing 5 w.t% micro ZnO and 0.866 cm for the ball clay containing 5 w.t% nano ZnO. We concluded from the HVL results that if the space in which the shield will be used is limited, the ball clay with nano ZnO is more useful because a thinner specimen with nano ZnO can attenuate half ofthe incoming photons. Scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy were used to investigate the properties of ZnO/ball clay.

Zn-doped Tin monoxide nanobelt induced engineering a graphene and CNT supported Zn-doped Tin dioxide composite for Lithium-ion storage

In this work, a rapid coprecipitation reaction is developed to obtain nano-sized Zn-doped tin oxide samples (Zn-SnO-II or Zn-SnO2-IV) for the first time by simply mixing tin ion (Sn2+ or Sn4+) and zinc ion (Zn2+) containing salts in a mild aqueous condition. Characterization results illustrate the Zn-SnO-II sample is constituted by an overwhelming quantity of Zn-doped SnO nanobelts and a small quantity of Zn-doped SnO2 nanoparticles. The redox reaction between the Sn2+ ions from the Zn-SnO-II sample and the surface oxygen-containing functional groups from functionalized carbon nanotube (F-CNT) and graphene oxide (GO) leads to the formation of the final Zn-SnO2/CNT@RGO composites. As an anode active material for lithium-ion batteries, the Zn-SnO2/CNT@RGO product showed superior electrochemical performance than the controlled Zn-SnO2/CNT and Zn-SnO2/RGO samples, which had a high gravimetric capacity of 901.3 mAh·g−1 at a high charge and discharge current of 1000 mA·g−1 after 300 cycles and excellent rate capability. The reaction mechanism for the successful synthesis of the Zn-doped tin oxide samples has been proposed, and the insight into the outstanding lithium-ion storage performance for the Zn-SnO2/CNT@RGO composite has been revealed. The synthetic processes for both the Zn-doped tin oxides and derived carbon supported composites are straightforward and involve no harsh conditions nor complicated treatment, which have good potential for massive production and application in wider fields.